Conversion and coking of hydrocarbons



Oct. 22, 1935. c. H. ANGELL 2,017,836

CON VERSION AND COKING OF HYDROCARBONS v Filed March 26, 1954 FRACTIONATQR FURNACE 6| 4; RECEIVER 1 VEN R CHAR 's .H. ANGELL TORNE-Y Patented Oct. 22, 1935 UNITED STATES CONVERSION AND COKING OF HYDBOCARBONS Charles H. Angeli, Chicago, Ill., assignor Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application March 26, 1934, Serial No. 717,319

6 Claims.

relatively low pressure, together with residual liquid resulting from the conversion of intermediate products of the process at substantial su-' peratmospheric pressure, while selected lowboiling fractions of the vaporous products from the coking operation, including any motor fuel components, are subjected, either alone or together with selected low-boiling intermediate products of the conversion stage of the process, to independently controlled conversion conditions regulated to materially improve the charracteristics of the motor fuel fractions, particularly with respect to anti-knock value, without excessively altering their boiling range and at the same time produce high yields of good quality motor fuel from any components of said low-boiling fractions boiling above the range of motor fuel.

The invention is particularly adapted to the treatment of charging stocks of a relatively highboiling nature such as heavy crudes, topped crude, fuel oil and residual oils generally, or oils of relatively wide boiling range, such as crude petroleum, for example, including crudes containing an appreciable quantity of gasoline or gasoline fractions of poor anti-knock value. vention also specifically contemplates the treatment of tars, pitches, asphaltic material and solid or semi-solid bituminous materials generally, including coal, peat, lignite, etc., preferably in finely divided state and in admixture with hydrocarbon oil.

The advantages obtained by the reduction of residual conversion products, resulting from the pyrolysis of hydrocarbon oils, to coke at relatively low pressure, as reflected in the increased yields of low-boiling liquid products, such as motor fuel, and the more uniform nature and low volatility of the coke produced, are well established. However, the low-boiling distillates within the range of motor fuel producedby such a coking operation, have been found in many cases, of inferior anti-knock value. I have further found, however, that these distillates, including, when desired, materials boiling somewhat above the range of motor fuel, may be converted under reforming conditions of elevated temperature and super-atmospheric pressure to produce additional high yields of motor fuel of exceptionally good anti-knock value.

The present invention offers an advantageous method of accomplishing this in i finib ilation The in-.

with the subjection of relatively heavy oil, oil of relatively wide boiling range or carbonaceous materials generally to coking, together with the residual liquid conversion products of the process, and in case the charging stock thus sub- 5 jected to coking contains materials within the boiling range of motorfuel, such as straightrun gasoline of low anti-knock value, for example, they may be recovered from the coking operation together with the other light distillates, 10 including motor fuel produced therein, and subjected to reforming therewith, to produce high yields of motor fuel ofmaterially improved antiknock value, while the intermediate products of the cracking and coking operations, including 15 any corresponding components of the charging stock which are not converted during the coking operation, are subjected in the same system to independently controlled conversion conditions best suited for their treatment.

Coking of the residualliquid conversion products of the process and heavy components of the charging stock may be accomplished in the present invention by subjecting either or both of these materials to heating, prior to their introduction 2 into a low-pressure coking zone, under conditions of temperature, pressure and time regulated to effect the production of coke therefrom upon their introduction into the coking zone without detrimental coke formation in the heating zone. 30 This particular feature of the invention possesses novelty in combination with the other features of the invention and is especially desirable in the present invention since it obviates the use of a heat carrying medium for the coking operation, 35 such as low-boiling oil heated to a high conversion temperature. Motor fuel of good antiknock value which would normally be produced from such low-boiling oils under the conditions of treatment to which they are best suited would be contaminated if introduced into the coking zone by the inferior motor fuel produced from the high-boiling oils subjected to coking. This would necessitate reforming treatment of the good quality motor fuel along with that of inferior quality since there is no economical method available for separating the two. However, it is not desired to limit the invention to this particular method of coking the heavy oils since any other well known method, including external heating of the coking zone as well as the introduction of suit-able heat carrying media into the coking zone may be employed, when desired.

One specific embodiment of the present invention comprises subjecting charging stockfor the process to conversion temperature in a heating ,coil under conditions regulated to preclude any excessive coke formation in this zone, introducing the heated materials into a low-pressure coking chamber wherein low-boiling vaporous components of the charging stock separate from the higher boiling residue and the latter is reduced to coke, separating any entrained high cokeforming materials, such as tars, pitches and the like, from the vapors and returning the same to the coking zone, subjecting the vaporous products from the coking zone to fractionation, whereby their high-boiling components are condensed as reflux condensate, subjecting fractionated vapors of the desired end-boiling point, including motor fuels produced in the coking operation as well as any motor fuel components of the charging stock escaping conversion in the coking operation, to condensation, collecting and separating the resulting distillate and gas, subjecting the reflux condensate to conversion temperature at superatm'ispheric pressure in a separate heating coil and communicating reaction chamber, separating the resulting vaporous and residual liquid conversion products, subjecting the residual liquid to coking, together with the charging stock, subjecting the vapors to fractionation in a separate fractionating zone, wherein their components boiling above the range of the desired final light distillate product of the process are condensed as reflux condensate, subjecting fractionated vapors of the desired end-boiling point to condensation, recovering the resulting distillate, separating the reflux condensate formed in said last mentioned fractionating zone into selected lowboiling and high-boiling fractions, returning the high-boiling fractions to the last mentioned heating coil for further conversion, subjecting the low-boiling fractions, together with said distillate recovered from vthe fractionator of the coking stage, to independently controlled conversion conditions oi elevated temperature and super- -atmospheric pressure in another separate heating coil and commingling the resulting heated products with the products resulting from said con----- version of the high-boiling reflux condensate, prior to said fractionation of their vaporous components.

As a modification of the specific embodiment of the invention above described, the total reflux condensate from the fractionator of the cracking stage of the system may be subjected to conversion, together with the reflux condensate resulting from fractionation of the vaporous products from the coking zone, in which case only the distillate recovered from the coking stage of the system is subjected to conversion in the last mentioned heating coil.

A more detailed description of the process of the invention above outlined, as well as several of the many possible modiflcationsthereof, will be found in connection with the following description of the accompanying diagrammatic drawing, which illustrates one speciflc form of apparatus in which the process may be carried out. It will be understood, of course, in connection with the following description of the drawing, that the invention is not limited to the specific form of apparatus illustrated and described and that the various alternative methods of operation mentioned are not to be considered equivalent but may be chosen to suit the particular nature of the materials undergoing treatment and the desired results.

. Referring to the drawing, charging stock for the process, which may comprise hydrocarbon oil or a mixture of liquid and suitable solid or semisolid hydrocarbons, as previously mentioned, is supplied through line I and valve 2 to pump 3,

by means of which it is fed through line 4 and 5 may pass through line 5, valve 6 and lines I and 8 to heating coil Ill. The charging stock may, of course, be preheated in any suitable well known manner, prior to its introduction into the heating coil. The drawing illustrates one specific method 10 whereby this may be accomplished by passing a regulated portion or all of the charging stock through valve II in line 4 to heat exchanger l2, wherein it is preheated by indirect contact with hot vaporous products from the coking zone, the 15 heated charging stock passing therefrom through line I3 and valve it into line I and thence through line 8 to heating coil I0.

Heating coil I0 is supplied with heat from furnace l5, of any suitable form, by means of which 20 the oil passing through the heating coil is heated to the. desired conversion temperature under suitable conditions of pressure (preferably superatmospheric) and time (velocity) to preclude any excessive coke formation in the heating coil and 25 connecting lines but at the same time heating the oil sufficiently to effect subsequent reduction of its residual components to coke. The heated materials are discharged from heating coil l0 through line l8 and may enter coking chamber 30 II at any suitable point in this zone, as indicated in the drawing by lines I8 controlled by valves l8.

Coking chamber I1 is preferably maintained at substantially atmospheric or relatively low superatmospheric pressure, of the order of pounds 35 or less, per square inch, and the coke formed in this zone is allowed to accumulate therein to be removed therefrom after the operation of the chamber is completed. When desired, a plurality of coking chambers similar to chamber I7, but 40 for furtheroperation so that the coking stage of 45 the process may be continuous.

Chamber i1 is provided with a suitable drainline 20 controlled by valve 2! which'may also serve as a means of introducing water, steam or any other suitable cooling medium into the cham- 50 her after its operation is completed, ,to hasten cooling and facilitate cleaning of the chamber.

In the particular case here illustrated, vapors are removed from the coking zone through line 22 and pass through valve 23 into heat exchanger 5 l2, wherein any high coke-forming components thereof, such as entrained particles of tar, pitch or the like, are removed by cooling, collecting as condensate in the lower portion of the heat exchanger, from which they may be withdrawn 60 through line 24 and valve 25 to pump 28, by meansof which they may be returned, all or in part, either through line 8 and valve 9 to heating coil I0 I or through line 21 and valve 28 to coking chamber i1, entering this zone at any desired point as indi- 65 cated by lines ll controlled by valves 12.

Vaporous products from the coking zone remaining uncondensed in heat exchanger I2 may pass therefrom through line 29 and valve 30 to fractionation in fractionator 3|, wherein their 70 high-boiling components are condensed as reflux condensate, as will be later more fully described.

It is, of course, within the scope of the invention to by-pass heat exchanger I2, supplying the vaporous products from the coking zone direct to 5 fractionator 3|, by well known means, not illustrated, or, when desired, to employ instead of or in conjunction with heat exchanger l2 any other suitable means of 'removing high coke-forming components and entrained liquids from the vapors.

Fractionated vapors of the desired end-boiling point, including conversion products within the boiling range of motor fuel, produced in the coking stage of the process as well as any motor fuel components of the charging stock, which latter will not ordinarily be subjected to any appreciable conversion in the coking stage, and also including, when desired, somewhat higher boiling materials such as naphtha, kerosene or kerosene distillate, pressure distillate bottoms and the like, are removed from the upper portion of fractionator 3| through line 32 and valve 33 and are subjected to condensation in condenser 34. The resulting distillate and gas passes through line 35 and valve 36 to collection and separation in receiver 31. Uncondensable gas may be released from the recelver through line 38 and valve 39. When desired, a regulated portion of the distillate may be withdrawn from receiver 31 through line 40 and valve 4| to storage or to any desired further treatment. Preferably, however, all or at least a portion of the distillate is withdrawn from receiver 31 through line 42 and valve 43 to pump 44, by means of which it is supplied through line 45, valve 46 and line 82 to further conversion in heating coil 47, as will be later more fully described.

.Refiux condensate formed in fractionator 3|, comprising the components of the vaporous products supplied to this zone boiling above the range of the desired light distillate product collected in receiver 31, is allowed to accumulate within the lower portion of fractionator 3| from which it is withdrawn through line 48 and valve 49 to pump 50 and supplied through line 5|, valve 52 and line 81 to further conversion in heating coil 53.

Heating coil 53 is located within a furnace 54, of any suitable form, which supplies the required heat to the oil passing through the heating coil to bring it to the desired conversion temperature, preferably at a substantial superatmospheric pressure. The heated oil is discharged through line 55, valve 55 and line 62 to reaction chamber 51.

Chamber 5'! is also preferably maintained at a substantial superatmospheric pressure, which may be substantially the same or somewhat lower than that employed at the outlet from the heating coil 53. Chamber 51 is also preferably well insulated, although not indicated in the drawing, in order to prevent excessive radiation and conserve heat so that conversion of the heated products supplied to this zone, and more particularly their vaporous components, may continue therein. In the particular case here illustrated both vaporous and liquid conversion products are withdrawn in commingled state from the lower portion of chamber 51 passing through line 58 and valve 59 to vaporizing chamber 60. It is, of course, also within the scope of the present invention to separately withdraw a regulated portion or substantially all of the vaporous conversion products from chamber 51 at any suitable point in this zone (not illustrated) in which case the vapors separately withdrawn may be supplied, all or in part, either to chamber 60 at any desired point or direct to fractionator 18 by well known means, not illustrated, while'the liquid conversion products, either alone or together with a regulated portion of the vapors, may be supplied to chamber 60, as illustrated, or may be directed by well'known means, not shown, to coking-chamber H or to heating coil Ill.

Heating coil 4'! is located within a furnace SI of any suitable form by means of which the oil passing through the heating coil is brought to the desired conversion temperature, preferably at a substantial superatmosphericpressure, although, when desired, relatively low pressures down to substantially atmospheric may be employed in this zone. Heated products are discharged from heating coil 4! through line 32 and may be directed, all or in part, either to reaction chamber 51 or tovaporizing chamber 60, enter ing either or both of these zones at any desired point therein. In the particular case here illustrated the heated products from heating coil 41 may pass through valve 63, in line 62, to commingle therein with the heated products from heating coil 53, passing therewith to chamber 51, or they may be diverted, all or in part, from line 62 through line 64 and valve 65 into line 58, commingling therein with the products passing from the lower portion of chamber 51 into vaporizing chamber 60.

Chamber 60, when such a zone is employed, is preferably operated at a substantially reduced pressure relative to that employed in the reaction chamber, by means of which further vaporization of the liquid conversion products supplied to this zone, as previously described, is accomplished. The residual liquid conversion products remaining unvaporized in chamber 80 may be withdrawn from the lower portion of this zone through line 66 and valve 51 to pump 68, by means of which they are fed through line 65 and may be directed, all or in part, through valve ID in this line into coking chamber II, entering this zone at any desired point or plurality of points, as indicated by lines 1i controlled by valves I2, or a regulated portion or all of the residual liquid may be diverted from line 69 through line i and valve 13 into line 8, passing therefrom into heating coil l0, together with the charging stock. It is, of course, also within the scope of the present invention to withdraw a regulated portion or all of the liquid residue produced in vaporizing chamber 60 from the system to cooling and storage or elsewhere, as desired. Line I4 controlled by valve 15 illustrates means whereby this may be accomplished. This permits the simultaneous production of both coke and liquid residue. when both are desired.

Vaporous products pass from the upper portion of chamber 60 through line I6 and valve 11 to fractionation in fractionator 18. The components of the vaporous products supplied to the fractionator boiling below the range of the desired final light distillate product of the process are condensed in this zone as reflux condensate, which may, when desired, be separated into selccted low-boiling and high-boiling fractions. When the reflux condensate is so separated, its low-boiling fractions may be withdrawn from any suitable intermediate point or plurality of points in the fractionator, for example through line 19 and valve 80, to pump 8| by means of which they are returned through line 82 and valve 83 to further conversion in heating coil 41, together with the distillate from receiver 31. The high-boiling fractions of the reflux condensate or the total reflux condensate, in case it is not separated into selected low-boiling and high-boiling fractions, may be withdrawn from the lower portion of fractionator 18 through crude, gas oil, uel oiland thelike.

88 to further conversion in heating coil 53, to-

gether with the reflux condensate fromfractionator 3!. i

Fractionatedjvapors of the'desired end-boiling point, comprisingth'e final light distillate product of the process, such, as motor fuel 'of high anti-knock value, are withdrawmtogether withuncondensable gasffromthe upper portion of fractionator '18 through'line 89 and valve 90, to be subjected to condensation and cooling in condenser 19!. The resulting distillate and gas passes through llne fll and valve 93 to collection and separation in'receiver 94; Uncondensable, gas may be through lineflliand valve 96Q Distillate maybe withdrawn from receiver 94 through line 91 and --range, forexample, from 900 to 1050 F and valve 98 to storageorto'any desired' further treatment. The usual expedient-s for controlling fractionation in fractionators 3i and 18 may, of 'course,.

be employed, although not illustrated' Such expedients may comprise, for example, returning regulated portions of the distillate products collected in receivers 31 and 94 to'the upper portion of the respective fractionators 3| and 18, to serve as refluxing material to cool an'd'assist fractionation of the vapors and maintain the de-' sired vapor outlet temperaturesfrom the fractionators.

It is also within thescopeof the invention.

when desired, to supply a separate charging stock to heating coil 41 or to heatingcoil 53or both, although well known means for accomplishing this are not shown in the drawing; In such cases the charging stocks so employed'are preferably within s bstantially the same boiling range as the materials from within thesystem with which they are subjectedto conversion. For example, such oils as straight-run gasoline,

naphtha, kerosene or kerosene distillate, pressure distillate, pressure distillate bottoms or the like may be suitable as'secondary charging stock for heating coil 41 while a secondary charging stock for heating coil 53 may comprise, for ex ample, such' ils as crude petroleum,

Ina process of the character illustrated and above described, the preferred range of operating conditions maybe approximately as follows: The heating coil to which the charging stock is supplied, either alone or together with-residual liquid conversion products of the process, may utilize .an outlet conversion temperature of the order of 825 to 950 F., preferably {with a substantial superatmospherid pressure of from 100 to 500 pounds, or more,'per'square inch, and pref erably, as already mentioned; theoil supplied to this zone is not maintained therein for a 'sufiicient length of time to allow any excessive coke-"formation and deposition in this zone. A relatively low pressure of the'order'of substantially atmospheric to 109 pounds, orthereab'ou'ts, per square inch is preferred in'the coking chamber and may be substantially equalized or somewhat reduced in the succeeding fractionating', condensing and collecting portions 'offthe coking stage. I The heating coil to which reflux condensate from the fractionator 'of the coking stage and the total orhighboiling fractionsof theireflux condensate from the cracking system are suppliedmay utilize a conversion temperature, measured at the outlet therefromof the ;order of 850 to 950 F., preferably with a substantially superatmospheric presreleased-from the receiver topped sure'at this point gin at system or fr m to,

' 500 pounds or more, persquare inch... Substantially the sameor somewhat lower pressure may be employed in the vreactionchamber and a subchamber, when. such a zone isemployed. The, pressures employed in "the fractionating, condensingand collecting portions of .the cracking stage may be substantially equalized or somewhat I reduced relative, to the pressure in the preceding portion-of the system. ,Theconversion temperature employedv at the'outlet from the heating coil to which distillate from thecoking stage of the 15 system, either alone or together with low-boiling fractions of the reflux condensate from the fractionator-of the cracking stage is supplied, may

preferably a substantial superatmospheric pres- 20 sure of from 200 to800 pounds, or, more, per

square inch is employed-at this point in the syspheric pressure of about 300 pounds per square 35 inch. Theheated-products are discharged into a coking chamber maintained at a superatmospheric pressure of about 30 pounds per square inch. Heavy tars and similar high coke-formingmaterials removed from the vaporous products 40 from the coking chamber, prior to their fractionation, are returned to the cokingchamber. The distillate recovered asthe overhead product from 1 the fractionator of the coking system has an end-' boiling pointof approximately 5505a Thehighor boiling components of the vapors, which are condensed as reflux condensate, are subjected in p a separate heating coil to an outlet conversion temperature of,- approximately 950 F at a superatmospheric pressure of about 350 pounds per I30 square inch and the heated products are intro-' duced into a reaction chamber maintained at ap-' proximately the same. pressure. The succeedingvaporizing chamber. is maintained at i a superat mospheric pressure of about 50 pounds per square 55 I inch and this pressure is substantiallyequalizedf in the succeeding fractionating, condensing and collecting portions of the crackingstage. 1 High boiling fractions of the reflux condensate from the cracking stage are returned to the sameheat c0 ing coil to which the reflux condensate from the fractionator of the coking stage is supplied. Low-' boiling. fractions of the reflux condensate from thefractionatorof the crac ing stage, having 'a' boiling range. of approximately lqoto 550 F., are 5 subjected in another separate heating coil, together with the distillaterecovered,frornjthe coking stage otthe system, to an outlet conversion temperature of approximately 980 F., at a super;

atmospheric pressurev of about, 800 pounds per 70 square-inch andthe heated products from this zone. are introduced into thevaporizing chamber. Thisoperation may, produce, per barrel of charging stock,, approximately 55% of 400 end-"- point motor fuel having an anti-knock 'va1ue 7 carbons, heating the reflux condensate to crackingtemperature under pressure while flowing in a restricted stream through a heating zone, passing the lighter fraction in a restricted stream through a second heating zone maintained at higher temperature than the first-named heating zone and heating the same therein suflicient- 1y to enhance the anti-knock value of its -gaso-' line content, commingling the thus heated lighter fraction with the heated reflux condensate discharged from the first-named heating zone, separating the commingled oils in a separating zoneinto vapors and residual oil, withdrawing such separated residual oil from the separating zone and introducing the same to said'coking zone and reducing it to coke therein in admixture with the chargin oil, separately removing the last-named vapors from the separating zone and fractionating and condensing the same.

2. A combined coking, cracking and reforming process which comprises distilling the charging oil to coke in a coking zone, fractionating resultant vapors to form a reflux condensate heavier than gasoline and a lighter fraction containing a substantial quantity of gasoline boiling hydrocarbons, heating the reflux condensate to cracking temperature under pressure while flowing in a restricted stream through a heating zone, passing the lighter fraction in a restricted stream through a second heating zone maintained at higher temperature than the first-named heating zone and heating the same therein sufficiently to enhance the anti-knock value of its gasoline content, commingling the thus heated lighter fraction with the heated reflux condensate discharged from the first-named heating zone, separating the commingled oils in a separating zone into vapors and residual oil, withdrawing such separated residual oil from the separating zone and introducing the same to said coking zone and reducing it to coke therein in admixture with the charging oil, separately removing the last-named vapors from the separating zone fractions thereof, supplying such condensed fractions to the first-named heating zone for retreatment therein together with said reflux condensate, and finally condensing the fractionated vapors.

3. A combined coking, cracking and reforming process which comprises distilling the charging oil to coke in a coking zone, fractionating resultant vapors to form a reflux condensate heavier than gasoline and a lighter fraction containing a substantial quantity of gasoline boiling hydrocarbons, heating the reflux condensate to cracking temperature under pressure while flowing in a restricted stream through a heating zone, passing the lighter fraction in a restricted stream through a second heating zone maintained at higher temperature than the first-named heating zone and heating the same therein sufficiently to enhance the anti-knock value of its gasoline content, commingling the thus heated lighter fraction with the heated reflux condensate dis-- charged from the first-named heating zone, separating the commingled oils in a separating zone into vapors and residual oil, withdrawing such separated residual oil from the separating zone and introducing the same to said coking zone and reducing it to coke therein in admixture with the charging oil, separately removing the last-named vapors from the separating zone and fractionating the same to form a relatively heavy reflux condensate and a lighter reflux condensate, supplying the former tothe first-named heating zone and the latter to said second heating zone for retreatment with the reflux condensate and the lighter fraction respectively or the coking operation, and finally condensing the fractionated vapors." y

4. A process for treating crude oil containing natural gasoline which comprises distilling the crude to coke in a coking zone, fractionating the resultant vapors to form areflux condensate heavier than gasoline and a lighter fraction containingthe low anti-knock gasoline hydrocarbons evolved from the crude, heating the reflux condensate to cracking temperature under pressure ina heating zone and subsequently discharging the same into a separating zone, heating the lighter fraction in a second heating zone to higher temperature than the reflux condensate in the first-named heating-zone and sufficiently to enhance the anti-knock value of its gasoline content, discharging the more highly heated lighter fraction. into the separating zone and separating the commingledv products in this zone into vapors and residual oil, discharging such separated residual oil from the separating zone into said coking zone and reducing the same to'coke therein in admixture with the crude oilfseparately removing the last-named vapors from the separating zone and iractionating and condensing the same.

5. A process for treating crude oil containing natural gasoline which comprises distilling the crude to coke in a coking zone, fractionating the resultant vapors to form a reflux condensate heavier than gasoline and a lighter fraction containing the low anti-knock gasoline hydrocarbons evolved from the crude, heating the reflux condensate to cracking temperature under pressure in a heating zone and subsequently discharging the same into a separating zone, heating the lighter fraction in a second heating 'zone to higher temperature than the reflux condensate in the first-named heating zone and sufficiently to enhance the anti-knock value of its gasoline content, discharging the more highly heated lighter fraction into the separating zone and separating the commingled products in this zone into vapors and residual oil, discharging such separated residual oil from the separating zone into said coking zone and reducing the same to coke therein in admixture with the crude oil, separately removing the last-named vapors from the separating zone and fractionating the same to condense heavier fractions thereof, supplying such condensed fractions to the first-named heating zone for retreatment therein together with said reflux condensate, and flnally condensing the fractionated vapors.

6. A process for treating crude oil. containing natural gasoline which comprises distilling the crude to cokein a coking zone, fractionating the resultant vapors to form a reflux condensate heavier than gasoline and a lighter fraction containing the low anti-knock gasoline hydrocar- .bonslevoived from the crude, heating the reflux condensate to cracking-temperature under pressure in a heating zone and subsequently discharging the same into a separating zone, heating the lighter fraction in a second heating zone to higher temperature than the reflux condensate in the first-named heating zone and sufliciently to enhance the anti-knock value of its gasoline content, discharging the more highly heated lighter fraction into the separating zone and separating the commingled products in this zone in'to vapors and residual oil, dischargingsuch separated residual oil from the separating zone into said coking zone and reducing the same to coke therein in admixture with the crude oil, separately removing the last-named vapors from the separating zone and iractionating the same to form a relatively heavy reflux condensate and a lighter reflux condensate, supplying the former to the first-named heating zone and the latter to said second heating zone for retreatinent with the reflux condensate and the lighter traction respectively of the coking operation, and flnaily 1o condensing the fractionated vapors.

CHARLES H. ANGEL. 

